Uni-control mechanism for simultaneously adjusting a plurality of tuning elements



March 7, 1953 A. E. CHELGREN 632,109

2 UNI-CONTROL MECHANISM FOR SIMULTANEOUSLY ADJUSTING A PLURALITY OF TUNING ELEMENTS Filed Dec. 22, 1950 INVENTOR. ARVID E. CHELGREN I0 [is 20 25 3O 0F COIL LENGTH BY H/S ATTORNEY Patentecl Mar. 17, 1953 UNITED STATES PATENT QFFICE UNI-CONTROL MECHANISM FOR SIMUL- TANEOUSLY ADJUSTING A PLURALITY OF TUNING ELEMENTS Arvid E. Chelgren, Elmhurst, Ill., assignor to Zenith Radio Corporation, a corporation of Illinois Application December 22, 1950, Serial No. 202,227

6 Claims. (01. 250-40) This invention relates to an improved uni-con a constant frequency difference therebetween "trol mechanism for simultaneously adjusting a throughout a relatively wide tuning range. plurality of tuning elements included in a wave- Accordingly, the invention provides a uni-consignal translating apparatus and is especially trol mechanism for simultaneously displacing a suited for use in a superheterodyne receiver for 5 plurality of movable tuning elements and is tuning the tracking circuits through predeteradapted to be included in a wave-signal transmined frequency ranges in a manner to provide lating apparatus. The uni-control mechanism a substantially constant frequency difference comprises a mounting base and a plurality of therebetween. lever-arms supported by the base for pivotal Although the invention may be employed with movement about a common reference axis. Each a variety of tuning elements, it is ideally suited of the lever-arms includes a portion for mefor uni-controlling a plurality of adjustable tunchanically engaging an assigned one of the tuning inductors individually comprising a cylin ing elements. A corresponding plurality of addrical coil and a tuning member of conductive justably fixed elements are individually disposed material supported in coaxial alignment with the between the reference axis and the engaging porcoil for movement into and out of one end theretion of an assigned one of the lever-arms; these of to constitute therewith a variable condenser. elements determine the effective distance from Such a tuning device, per se, is disclosed in the the reference axis to the engaging portions. An copending application of Arvid E. Chelgren, actuator in mechanical coupling engagement Serial No. 146,845, filed February 28, 1950, now 0 with the lever-arms effects concurrent displace- Patent No. 2,595,764 granted May 6, 1952, and ment of the lever-arms about the reference axis. assigned to the same assignee as the present ap- The features of the present invention which plication. are believed to be novel are set forth with par- The problem of uni-controlled adjustment of a ticularity in the appended claims. The present plurality of tunable devices is exceedingly old in invention itself, both as to its organization and the receiver art and is encountered in all supermanner of operation, together with further obheterodyne receivers where it is necessary to acjects and advantages thereof may best be undercomplish simultaneous tuning of radio-fr stood by reference to the following description quency selectors and the heterodyne oscillator taken in connection with the accompanying while maintaining a preselected frequency reladrawings in which:

tion between the tunable stages over the desired Fig. 1 is a plan view of a uni-control mechrange of operating frequencies. Usually, each of anism in accordance with the invention;

the tunable stages has a principal tuning re- Fig. 2 is a sectional view taken along line 2-2 actance, such as a variable inductor or condenser, of Fig. l

:and the uni-control mechanism adjusts those re- Fig. 3 represents the electrical equivalent of actances. In most instances, however, this sort a portion of the apparatus shown in Fig. 1; and, "of arrangement provides the precise frequency Fig. 4 comprises curves representing certain relation of the tunable stages over but a small electrical performance characteristicsv of a porportion of the operating range and it is necestion of the structure of Fig. 1.

sary to resort to the use of trimmer and/or pad- Referring now to Fig. 1, the uni-control mechder condensers in an effort to achieve tracking, anism I0, constructed in accordance with the that is, a relatively fixed frequency relation of instant invention, is associated with the tuning the tunable Stages Over the entire pe ating elements of a wave-signal translating apparatus an W th uch au y un ng aids tracksuch as a receiver of the superheterodyne type. ing may be approximated but it is desirable to The units If and I2 when considered as part of efiect precise tracking Without trimmer 0011- a superheterodyne receiver may constitute a tundensers and the like while at the same time proable radio-frequency selector and the frequencyvidingatuning system that is flexible. determining circuit of the local or heterodyne It is an object of this invention, therefore, to oscillator. Since the circuitry of that type reprovide an improved uni-control mechanism for ceiver is thoroughly understood in the art and simultaneously adjusting a plurality of tuning constitutes no part of the present invention, the

elements. remainder of the receiving apparatus has been It is another object of the invention to proomitted from the drawing and the following devide an improved uni-control mechanism for adscription will be limited to the tunable devices I I lusting a nmrafityof tunable devices to produce and I2 and the uni-control mechanism for adjusting them. Of course, in many applications and even in particular superheterodyne receiver designs it is necessary to have the uni-control system extend to three or more tunable devices but, for the sake of simplicity, it is shown only in relation to a pair of tuning elements. Its extension to any number of such elements will be manifest from the discussion of the specific illustration. Moreover, for convenience, elements H and I2 will be assumed to be identical in construction.

As shown in Fig. 2, each of the tuning devices includes a pair of relatively movable components represented by an inductor I4 and an associated tuning core l6. Each such inductor comprises a plurality of conductive spirally-wound selfsupporting turns while the tuning core is a cylinder or rod of electrically conductive but non-magnetic material. To facilitate uni-controlled adjustment of these devices it is preferred that the inductors be supported in substantially parallel relation with one another as by mounting the inductors with their axes normal to a mounting base 2|. The mounting arrangement for coil M of tuning device H, for example, comprises a shield container l3 enclosing the inductors and afiixed in any desired manner to base 2|. The lowermost end of the inductor is electrically connected to the bottom closure portion of the container as indicated to s pport the inductor at that end. The opposite end of the inductor abuts against the shoulder of a member comprised of a disc 39 and a cylindrical portion |5 which projects into the top turns of coil M. Member Hi, 39 is formed of insulating material and has a central aperture in coaxial alignment with the internal bore of coil M. A conductive cap |9 closes the corresponding end of container I3 and has a centrally located cluster of conductive fingers 2|! for engaging tuning core I6. The channel formed by these fingers and the aperture of member Hi, 39 constitute a guide determining the path of movement of the tuning core 13 relative to inductor M. More specifically, this guide arrangement permits movement of the core axially of the coil, into and out of the upper end thereof. In order to vary the tuning characteristics of the tuning devices relative to each other, it is desirable to provide a further core member H at the lower end of the inductor. This core may also be constructed of electrically conductive but non-magnetic material and it is adjustably fixed in the base of shield l3 for inductance-trimming of inductor M. A threaded rod |8 to which this core is attached passes through, a threaded opening in the bottom of the shield and through an aligned opening in base 2|. It is convenient to slot the exposed end of this rod so that the position of core l1 may be subject to screw-driver adjustment.

Electrical connections to the tuning device may be made in a variety of ways. As represented in Fig. 2, an insulating bushing 50 carrying an inductive loop 5| projects through one side opening of container |3 to couple the loop and the apparatus connected thereto (not shown) to coil l4. Another lead 52 is connected to a tap on coil M and extends through another insulating bushing 53 accommodated by a side opening of the container. Connections to this lead and to the shield container may be employed to couple the tuning device to the circuit components.

This tuning device is similar to that described in the afore-mentioned copending application and its equivalent electrical circuit is repre- This correspondence of circuit components between Figs. 2 and 3 is obvious except for the condenser of Fig. 3. denser has the tuning core It as one electrode and has the enveloping turns of inductor Hi as the other electrode with the coil form I5 serving as an intervening dielectric. The condenser is shown as variable because the effective areas of the electrodes and the capacitance exhibited are determined by the position of core is within inductor M.

The uni-control mechanism W for simultaneously tuning devices H and I2 includes a carriage 22 having a pair of sidewardly extending, pointed projections 23. Each of these projections is received by an aperture 2 1 in a respective one of a pair of ears 25 of a bearing or pivot member 26 which extends upwardly from base 2| to provide a pivotal support for carriage 22. A plurality of levers 21 and 28 of adjustably fixed length are supported on the upper surface of carriage 22 for pivotal movement toward and away from the upper ends of the inductors of tuning devices H and I2. Each lever is also movable along the carriage 22 to adjust its effective length and guide means, such as projections 29 and 30 struck from carriage 22, engage the sides of the levers so that this movement is linear. A locking arrangement releasably locks each lever in adjusted position on the carriage.

The locking arrangement comprises a member 3| slotted for screw-driver adjustment and having a cam section 32 received in an opening 33 of its particular lever. An extension 32 of this member projects through an aperture of carriage 22 and is upset over a friction washer 35. The cam section 32 is eccentric relative to the extension 34 and rotation of the cam displaces the associated lever along its longitudinal axis and relative to carriage 22. The friction washer maintains the lever in any of its adjusted positions so that the lever may be said to have an adjustably fixed length.

Preferably, the free end of each lever 21 and 28 overlies one of the tuning elements H and i2 and has a threaded opening receiving a screw 36. A leaf spring 31 is fixed to the underside of each lever and is biased against the lower extremity of a respective one of screws 36. An individual flexible coupler 38, which preferably is constructed of a stiff, resilient wire, such as piano wire, extends from the free extremity of each spring 31 to the upper end of the particular tuning core l6 aligned with each lever. In other words, each coupler suspends one tuning core at an adjustably fixed distance from the free end of one of the actuating levers 21 and 28 to effect axial displacement of the tuning core in response to pivotal movement of its actuating lever. The adjustment permitted by the screws 36 is also useful in correlating the frequency characteristics of the several tuning devices, as will be described hereinafter.

The uni-control mechanism further includes means supported by base 2| for simultaneously displacing levers 21 and 28 about their common pivotal axis defined by the upper edge of support member 26 simultaneously to displac the tuning cores l6 of tuning elements and'lZ along their respective paths. This means comprises a cam 4| carried by a shaft 42 rotatably supported in suitable bearings mounted on base 2| for rotation about an axis parallel to member 26 but on the side thereof opposite tuning devices and I2. The carriage 22 has a horizontally disposed cam-follower portion 43 maintained in engagement with cam 4| by a bias spring 44. A control knob 45 attached to one end of shaft 42 facilitates controlled rotation of the shaft. It is evident that the distance through which each tuning core I6 is displaced as cam 4| turns with shaft 42 depends upon the distance from the pivot defined by aperture 24 of member 26 to the coupler 36, 38 of each core. This distance is adjustable by the members 3| which vary the effective lengths of the actuating levers 21, 28. It is apparent that by suitably proportioning the distances from the pivotal axis of carriage 22 to the tuning cores and to the cam and follower 4|, 43, the mechanical advantage of the lever so defined may be preset at any desired value.

In considering the operation of the described arrangement, let it be assumed that curve 46 of Fig. 4 represents the frequency characteristic of one of the tuning devices, say unit H, in terms of axial displacement of its tuning core l6. Since the position of the core depends on the position of cam 4|, the curve also denotes the variation in resonant frequency with rotation of shaft 42. Assuming further that the tuning devices are in the radio-frequency and heterodyning units of a superheterodyn receiver, the proper frequency characteristic for device I2 is represented by curve 41 but, before the system is adjusted, the frequency of device l2 with rotation of shaft 42 may vary as indicated in curve 48. Where this characteristic is obtained, the frequency separation of devices H and 2 is too small at one end of the operating range and the separation is too irregular. By adjustment of the auxiliary core of unit |2, the desired separation may be obtained at the high-freouency end of the range. Moreover, turning members 3| to adjust the relative lengths of the levers 21 and 28 permits the devices to tune over suitable ranges of frequency and adjustment of the coupler screws 36 enables the required frequency separation or tracking to be realized. While generally th adjustments are not entirely independent of one another, the system has a sufficient number of degrees of freedom to achieve efiicient tracking with a relatively simple control mechanism.

While a particular embodiment of the present invention has been shown and described, it will be obvious to those skilled in the art that changes and modifications may be made without departing from this invention in its broader aspects, and, therefore, the aim in the appended claims is to cover all such changes and modifications as fall within the true spirit and scope of this invention.

I claim:

1. In a wave-signal translating apparatus, a uni-control mechanism for simultaneously displacing a plurality of movable tuning elements, said uni-control mechanism comprising: a mounting base; a plurality of lever-arms supported by said base for pivotal movement about a common reference axis and individually having a portion for mechanically engaging an assigned one of said tuning elements; a corresponding plurality of adjustably fixed elements individually disposed between said reference axis and said portion of an assigned one of said leverarms for determining the effective distance from said reference axis to said portion of its associated lever arm; and an actuator in mechanical coupling engagement with said plurality of lever-arms for eifecting concurrent displacement of said lever-arms about said reference axis.

2. In a wave-signal translating apparatus, a uni-control mechanism for simultaneously displacing a plurality of movable tuning elements, said uni-control mechanism comprising: a mounting base; a plurality of lever-arms supported by said base for pivotal movement about a common reference axis; a corresponding plurality of coupling devices individually adjustably fixed to a respective one of said lever-arms for mechanically linking said lever-arm to an assigned one of said tuning elements and for adjusting the effective distance between said leverarm and said tuning element; a corresponding plurality of adjustably fixed elements individually disposed between said reference axis and said coupling devices for determining the effective distance from said reference axis to each of said coupling devices; and an actuator in mechanical coupling engagement with said plurality of leverarms for effecting concurrent displacement of said lever-arms about said reference axis.

3. In a wave-signal translating apparatus, a uni-control mechanism for simultaneously displacing a plurality of movable tuning elements, said uni-control mechanism comprising: a mounting base; a plurality of lever-arms supported by said base for pivotal movement about a common reference axis; a corresponding plurality of resilient coupling devices individually adjustably fixed to a, respective one of said leverarms for mechanically linking said lever-arm to an assigned one of said tuning elements and for adjusting the efiective distance between said lever-arms and said tuning element; a corresponding plurality of adjustably fixed elements individually disposed between said reference axis and said resilient coupling devices for determining the efiective distance from said reference axis to each of said resilient coupling devices; and an actuator in mechanical coupling engagement with said plurality of lever-arms for effecting concurrent displacement of said leverarms about said reference axis.

4. In a wave-signal translating apparatus, a uni-control mechanism for simultaneously displacing a plurality of movable tuning elements, said uni-control mechanism comprising: a mounting base; a plurality of lever-arms supported by said base for pivotal movement about a common reference axis; a plurality of guides supported by said base for limiting movement of said tuning elements to a predetermined path; a corresponding plurality of coupling devices individually adjustably fixed to a respective one of said lever-arms for mechanically linking said lever-arm to an assigned one of said tuning elements and for adjusting the effective distance between said lever-arm and said tuning element; a corresponding plurality of adjustably fixed elements individually disposed between said reference axis and said coupling devices for determining the effective distance from said reference axis to each of said coupling devices; and an actuator in mechanical coupling engagement with said plurality of lever-arms for effecting concurrent displacement of said lever-arms about said reference axis.

5. In a wave-signal translating apparatus, a uni-control mechanism for simultaneously displacing a plurality of movable tuning elements,

epeagioe 7 said uni-control 'mechanism comprising: 'a mounting base; means, including a carriage supported by said base for pivotal movement about a reference axis, providing a plurality of leverarms individually having a portion for mechanically engaging an assigned one of said tuning elements; a corresponding plurality of adjustably fixed elements supported by said carriage and individually disposed between said reference axis and said portion of an assigned one of said lever-arms for determining the effective distance from said reference axis to said portion of its associated leverarm; and an actuator in mechanical coupling engagement With said plurality of lever-arms for eiiecting concurrent pivotal displacement of said lever-arms about said reference axis.

6. In a Wave-signal translating apparatus, a uni-control mechanism for simultaneously diuplacing a plurality of movable tuning elements, said uni-control mechanism comprising: a mounting base; means, including a carriage supported by said base for pivotal movement about a reference axis, providing a plurality of leverarms individually having a portion for mechanically engaging an assigned one of said tuning elements; a corresponding plurality of cams adjustably supported by said carriage and individually disposed between said reference axis and said portion of an assigned one of said leverarms for determining the effective distance from said reference axis to said portion of its associated lever-arm; and an actuator in mechanical coupling engagement with said plurality of lever-arms for effecting concurrent pivotal displacement of said lever-arms about said reference axis.

ARVID E. CHELGREN.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,137,435 Yolles Nov. 22, 1938 2,483,105 Rennick Sept. 27, 1949 2,518,930 Polydorofi Aug. 15, 1950 

